Thermal Underwear, Long underwear, or Long Johns

Maybe you're an avid extreme winter mountain trekker or you simply get the chills while working in the cool office, you operate heavy mining equipment year round or you work for the US Coast Guard. Either way, thermal long underwear, also known as base layer or long johns, may be just what you need to stay warm and comfortable. The type you choose will depend on your activity level, your budget, and the temperature.